#include <cstring>
#include <iostream>
using namespace std;


int main()
{
    int hash[26];
    memset(hash, 0, sizeof(hash));
    std::string str;
    while(getline(cin, str))
    {
        int n = str.size();
        for(int i = 0; i < n; i++)
        {
            if(str[i] == ' ')
            {
                continue;
            }
            hash[str[i] - 'a'] += 1;
            // cout << str[i] << " " << endl;
        }
        cout << endl;
    }
    int ret = 0;
    char ch;
    for(int i = 0; i < 26; i++)
    {
        if(hash[i] > ret) 
        {
            ch = 'a' + i;
            ret = hash[i];
        }
    }
    cout << ch;
    return 0;
}